title: Adjusted exponentially tilted likelihood with applications to brain morphology.
abstract: In this article, we develop a nonparametric method, called adjusted exponentially tilted (ET) likelihood, and apply it to the analysis of morphometric measures. The adjusted exponential tilting estimator is shown to have the same first-order asymptotic properties as that of the original ET likelihood. The adjusted ET likelihood ratio statistic is applied to test linear hypotheses of unknown parameters, such as the associations of brain measures (e.g., cortical and subcortical surfaces) with covariates of interest, such as age, gender, and gene. Simulation studies show that the adjusted exponential tilted likelihood ratio statistic performs as well as the t-test when the imaging data are symmetrically distributed, while it is superior when the imaging data have skewed distribution. We demonstrate the application of our new statistical methods to the detection of statistically significant differences in the morphology of the hippocampus between two schizophrenia groups and healthy subjects.
authors.affiliation: Department of Biostatistics and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. hzhu@bios.unc.edu
authors.forename: Hongtu
authors.initials: H
authors.lastname: Zhu
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhou
authors.forename: Jiahua
authors.initials: J
authors.lastname: Chen
authors.forename: Yimei
authors.initials: Y
authors.lastname: Li
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lieberman
authors.forename: Martin
authors.initials: M
authors.lastname: Styner
mesh_terms: D001921:Brain / Q000473:pathology*; D003627:Data Interpretation, Statistical; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016013:Likelihood Functions; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology*; D012680:Sensitivity and Specificity